Table 2.
Summary of multiple linear regression models for tamoxifen and selected metabolites
| Metabolite/time point | r2 | F | P valuea | Parameters in the model |
|---|---|---|---|---|
| Tam 3 months | 0.212 | 19.750 | < 0.001 | Medium adherence; age at diagnosis |
| Tam 6 months | 0.161 | 9.520 | < 0.001 | Low and medium adherence; age at diagnosis |
| Tam 12 months | 0.471 | 39.130 | < 0.001 | Low and medium adherence |
| DM‐Tam 3 months | 0.412 | 8.995 | < 0.001 | CYP2D6 PM/IM, IM/IM, EM/PM, EM/IM; medium adherence; age at diagnosis; Asian/Indian ethnicity |
| DM‐Tam 6 months | 0.217 | 4.384 | < 0.001 | CYP2D6 PM/PM, EM/PM; low and medium adherence; age at diagnosis |
| DM‐Tam 12 months | 0.427 | 10.451 | < 0.001 | CYP2D6 PM/IM, EM/PM, EM/IM; low and medium adherence; age at diagnosis |
| Z‐Endo 3 months | 0.345 | 7.370 | < 0.001 | CYP2D6 PM/PM, PM/IM, EM/PM; medium adherence; Asian/Indian ethnicity |
| Z‐Endo 6 months | 0.322 | 8.421 | < 0.001 | CYP2D6 PM/PM, PM/IM, EM/PM, IM/IM; medium adherence |
| Z‐Endo 12 months | 0.403 | 10.877 | < 0.001 | CYP2D6 PM/PM, PM/IM, EM/PM, IM/IM; low and medium adherence |
| Metabolic ratio | ||||
| DM‐Tam/Z‐Endo 3 months | 0.556 | 30.002 | < 0.001 | CYP2D6 PM/IM, IM/IM, EM/PM, EM/IM |
| DM‐Tam/Z‐Endo 6 months | 0.510 | 20.195 | < 0.001 | CYP2D6 PM/IM, IM/IM, EM/PM, EM/IM |
| DM‐Tam/Z‐Endo 12 months | 0.575 | 15.540 | < 0.001 | CYP2D6 PM/IM, EM/PM, EM/IM; black ethnicity |
Cytochrome P450 2D6 (CYP2D6) diplotypes PM/PM, two null alleles; DM‐Tam, N‐desmethyltamoxifen; EM/IM, one normal and one reduced activity allele; EM/PM, one normal and one null activity allele; EM/UM, patient with gene duplications of alleles with normal activity; F, F‐test (ANOVA) for the model; IM/IM, two reduced activity alleles; PM/IM, one null activity and one reduced activity allele; r 2, model's coefficient of determination; Tam, tamoxifen; Z‐Endo, (Z)‐endoxifen.
a
Significance value of F‐test (analysis of variance) for the proposed model.